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Oil-cooled screw compressor and control method therefor

a screw compressor and oil cooling technology, applied in the direction of machines/engines, liquid fuel engines, positive displacement liquid engines, etc., can solve the problems of reducing the pressure of the oil separation and collection device, and the inability to supply the request pressure immediately

Active Publication Date: 2020-09-29
KOBELCO COMPRESSORS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention allows for maintaining a consistent moisture level and pressure in the oil separating and collecting device. This prevents moisture from accumulating and ensures that a high level of pressure is available for delivery immediately.

Problems solved by technology

Moreover, since the air is released during the state of the moisture discharge operation, a pressure of the oil separating and collecting device decreases.
Furthermore, even if the oil-cooled screw compressor enters a high load state where the request pressure is high, the request pressure cannot instantly be supplied because the presser inside the oil separating and collecting device decreases.

Method used

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  • Oil-cooled screw compressor and control method therefor
  • Oil-cooled screw compressor and control method therefor
  • Oil-cooled screw compressor and control method therefor

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Experimental program
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first embodiment

[0025]As shown in FIG. 1, an oil-cooled screw compressor 2 of the present embodiment includes an air passage 4 in which air mainly flows, and an oil passage 6 in which oil used for lubrication and cooling flows.

[0026]The air passage 4 is provided with a compressor body 8, an oil separating and collecting device 10, and an air release valve 12.

[0027]The compressor body 8 is of an oil-cooled screw type, and sucks air from a suction port 8a through first air piping 4a. To the compressor body 8 is mechanically connected a motor (an electric motor) 14, and driving the motor 14 allows the air to be compressed by an inside screw not shown. To the motor 14 is electrically connected an inverter 16, so that a rotational speed of the motor 14 can be changed. The compressor body 8 discharges compressed air from a discharge port 8b after compression. The discharged compressed air contains a large amount of oil, and is supplied to the oil separating and collecting device 10 through second air pip...

second embodiment

[0040]FIG. 4 shows a schematic configuration diagram of the oil-cooled screw compressor 2 of a second embodiment. The oil-cooled screw compressor 2 of the present embodiment is substantially similar to that of the first embodiment in FIG. 1 except that the first air piping 4a is provided with a suction flow rate sensor 38 and a suction humidity sensor 40. Accordingly, descriptions of similar portions to the configurations shown in FIG. 1 will be omitted.

[0041]In the present embodiment, the first air piping 4a is provided with the suction flow rate sensor 38 to detect the suction flow rate Qs to the compressor body 8, and the suction humidity sensor 40 to detect the suction humidity Ms to the compressor body 8. The suction flow rate sensor 38 and the suction humidity sensor 40 output respective measured values to the controller 30.

[0042]As shown in FIG. 5, the arithmetic operation section 36 of the present embodiment calculates the remaining moisture amount Dr on the basis of the mea...

third embodiment

[0045]FIG. 6 is a schematic configuration diagram of the oil-cooled screw compressor 2 of a second embodiment. The oil-cooled screw compressor 2 of the present embodiment is substantially similar to that of the first embodiment in FIG. 1 except that a suction valve 42 is added to the first air piping 4a. Accordingly, descriptions of similar portions to the configurations shown in FIG. 1 will be omitted.

[0046]In the present embodiment, the first air piping 4a is provided with the suction valve 42 to adjust a supply amount of the air to the compressor body 8. Moreover, the controller 30 further includes a suction valve control section configured to control the suction valve 42 so as to close the same when the discharge pressure Pd exceeds a predetermined air release pressure. The air release valve control section 34 of the present embodiment controls the air release valve 12 so as to open the same when the discharge pressure Pd exceeds the predetermined air release pressure.

[0047]In t...

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Abstract

An oil-cooled screw compressor includes a controller having an arithmetic operation section for arithmetically determining a remaining moisture amount Dr from at least a suction temperature Ts, a suction pressure Ps, a discharge temperature Td, and a discharge pressure Pd, an inverter control section for comparing a first rotational speed of a motor at which the remaining moisture amount Dr becomes the target moisture amount and a second rotational speed of the motor at which a discharge pressure Pd becomes the target pressure, and for controlling an inverter so as to drive the motor at the larger one of the first and second rotational speeds, and an air release valve control section for opening an air release valve while the discharge pressure Pd exceeds an air release pressure when the motor is driven at the first rotational speed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a national phase application in the United States of International Patent Application No. PCT / JP2016 / 071408 with an international filing date of Jul. 21, 2016, which claims priority of Japanese Patent Application No. 2015-160052 filed on Aug. 14, 2015 the contents of which are incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to an oil-cooled screw compressor and a control method therefor.BACKGROUND ART[0003]There has been known an oil-cooled screw compressor using oil for cooling and lubrication. Air sucked by the oil-cooled screw compressor contains moisture, so that the moisture may be deposited by the compressor and the like. Mixing the deposited moisture with lubricating oil causes a decrease in lubrication function.[0004]JP 2004-11426 A has disclosed an oil-cooled screw compressor in which in order to prevent the above-described deposition of the moisture, a moisture amount accumulated in lu...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): F04C28/24F04C29/02F04C28/28F04C28/08F04C18/16F04B39/16F04C29/04F04C29/00
CPCF04B39/16F04C28/08F04C18/16F04C28/24F04C29/026F04C29/04F04C29/0007F04C28/28F04C29/0085F04C29/12
Inventor FUJIWARA, YUICHI
Owner KOBELCO COMPRESSORS CORP